Nucleus Size Determination for Nd_2Fe_(14)B, Sm_2Co_(17), SmCo_5 and BaFe_(12)O_(19) Magnets

摘要

The nucleus size was determined for the following phases: Nd_2Fe_(14)B, Sm_2Co_(17), SmCo_5 and BaFe_(12)O_(19). These phases are the basis for the most relevant sintered permanent magnets. For the determination, it was assumed a spherical grain, and that the reversal of magnetization occurs in a tiny shell near the surface. The Magnetostatic energy for each domain configuration was found by means of Legendre polynomials. The nucleus is a spherical cap, near the equator. After reaching the nucleus critical size, the reversal of magnetization continues spontaneously, reducing the global energy of the system. It was found that, for each grain size, there is a different nucleus size.